Schedule of Calculation of Numerator and Denominator in Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income, Basic	$ 50,047	$ 46,307
Net income, Diluted	$ 50,047	$ 46,307
Weighted average common shares outstanding, Basic	117,782	117,235
Weighted average common shares outstanding, Basic	117,782	117,235
Weighted average shares and assumed conversions	118,259	117,769
BASIC EARNINGS PER SHARE	$ 0.42	$ 0.39
DILUTED EARNINGS PER SHARE	$ 0.42	$ 0.39
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	420	432
Restricted stock based awards
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	57	102